Alkylaromatics Production Using Dilute Alkene

ABSTRACT

A process for producing an alkylated aromatic product in a reactor by reacting an alkylatable aromatic compound feedstock with another feedstock comprising alkene component and alkane component in a reaction zone containing an alkylation catalyst. The reaction zone is operated in predominantly liquid phase without inter-zone alkane removal. The polyalkylated aromatic compounds can be separated as feed stream for transalkylation reaction in a transalkylation reaction zone.

FIELD

The present invention relates to a process for producing alkylatedaromatic products, particularly ethylbenzene and cumene.

BACKGROUND

Ethylbenzene is a key raw material in the production of styrene and isproduced by the reaction of ethylene and benzene in the presence of anacid alkylation catalyst. Older ethylbenzene production plants, thosetypically built before 1980, used AlCl₃ or BF₃ as the acidic alkylationcatalyst. Plants built after 1980 have in general used zeolite-basedacidic catalysts as the alkylation catalyst.

Commercial ethylbenzene manufacturing processes typically require theuse of concentrate ethylene that has a purity exceeding 80 mol. %. Forexample, a polymer grade ethylene has a purity exceeding 99 mol. %ethylene. However, the purification of ethylene streams to attainchemical or polymer grade is a costly process and hence there isconsiderable interest in developing processes that can operate withlower grade or dilute ethylene streams. One source of a dilute ethylenestream is the off gas from the fluid catalytic cracking orsteam-cracking unit of a petroleum refinery. The dilute ethylene stream,after removal of reactive impurities, such as propylene, typicallycontains about 10-80 mol. % ethylene, with the remainder being ethane,hydrogen, methane, and/or benzene.

Three types of ethylation reactor systems are used for producingethylbenzene, namely, vapor phase reactor systems, liquid phase reactorsystems, and mixed phase reactor systems.

In vapor-phase reactor systems, the ethylation reaction of benzene andethylene is carried out at a temperature of about 350 to 450° C. and apressure of 690-3534 KPa-a (6-35 kg/cm²-g) in multiple fixed beds ofzeolite catalyst. Ethylene exothermicly reacts with benzene to formethylbenzene, although undesirable reactions also occur. About 15 mol. %of the ethylbenzene formed further reacts with ethylene to formdi-ethylbenzene isomers (DEB), tri-ethylbenzene isomers (TEB) andheavier aromatic products. All these undesirable reaction products arecommonly referred as polyethylated benzenes (PEBs).

By way of example, vapor phase ethylation of benzene over thecrystalline aluminosilicate zeolite ZSM-5 is disclosed in U.S. Pat. Nos.3,751,504 (Keown et al.), 3,751,506 (Burress), and 3,755,483 (Burress).

In most cases, vapor phase ethylation systems use polymer grade ethylenefeeds. Moreover, although commercial vapor phase processes employingdilute ethylene feeds have been built and are currently in operation,the investment costs associated with these processes is high.

In recent years the trend in industry has been to shift away from vaporphase reactors to liquid phase reactors. Liquid phase reactors operateat a temperature of about 150-280° C., which is below the criticaltemperature of benzene (290° C.). The rate of the ethylation reaction islower compared with the vapor phase, but the lower design temperature ofthe liquid phase reaction usually economically compensates for thenegatives associated with the higher catalyst volume.

Liquid phase ethylation of benzene using zeolite beta as the catalyst isdisclosed in U.S. Pat. No. 4,891,458 and European Patent PublicationNos. 0432814 and 0629549. More recently it has been disclosed thatMCM-22 and its structural analogues have utility in thesealkylation/transalkylation reactions, for example, U.S. Pat. No.4,992,606 (MCM-22), U.S. Pat. No. 5,258,565 (MCM-36), U.S. Pat. No.5,371,310 (MCM-49), U.S. Pat. No. 5,453,554 (MCM-56), U.S. Pat. No.5,149,894 (SSZ-25); U.S. Pat. No. 6,077,498 (ITQ-1); InternationalPatent Publication Nos. WO97/17290 and WO01/21562 (ITQ-2).

Commercial liquid phase ethylbenzene plants normally employ polymergrade ethylene. Moreover, although plants can be designed to acceptethylene streams containing up to 30 mol. % ethane by increasing theoperating pressure, the costs associated with the design and operationof these plants have proven to be significant.

Technology has also been developed for the production of ethylbenzene ina mixed phase using reactive distillation. Such a process is describedin U.S. Pat. No. 5,476,978. Mixed phase processes can be used withdilute ethylene streams since the reaction temperature of the ethylationreactor is below the dew point of the dilute ethylene/benzene mixture,but above the bubble point. The diluents of the ethylene feed, ethane,methane and hydrogen, remain essentially in the vapor phase. The benzenein the reactor is split between vapor phase and liquid phase, and theethylbenzene and PEB reaction products remain essentially in the liquidphase.

U.S. Pat. No. 6,252,126 discloses a mixed phase process for producingethylbenzene by reaction of a dilute ethylene stream containing 3 to 50mol. % ethylene with a benzene stream containing 75 to 100 wt. %benzene. The reaction is conducted in an isothermal ethylation sectionof a reactor, which also includes a benzene stripping section, where theunreacted benzene is thermally stripped from the ethylation products.Integrated, countercurrent vapor and liquid traffic is maintainedbetween the ethylation section and the benzene stripping section.

U.S. patent application Ser. No. 10/252,767 discloses a process for theproduction of ethylbenzene by reacting benzene with a dilute ethylenestream containing 20 to 80 wt. % ethylene and ethane. The reaction takesplace in one of a series of series-connected reaction zones in thepresence of an alkylation catalyst including a molecular sieve such asMCM-22. The temperature and pressure of the reaction zone being suchthat the benzene and dilute ethylene feedstock are under liquid phaseconditions. The intermediate products between reaction zones are cooledand a portion of alkane, e.g., ethane, in the intermediate products isremoved to maintain liquid phase by avoiding accumulation of ethane fromzone to zone.

This invention relates a process for producing an alkylated aromaticcompound in predominantly liquid phase alkylation reactor with an alkenefeedstock containing alkene and at least 1 mol. % alkane withoutinter-zone alkane removal.

SUMMARY OF THE INVENTION

In one embodiment, this invention relates to a process for producing analkylated aromatic compound in a reactor having a plurality of reactionzones including a first reaction zone and a second reaction zone, theprocess comprises the steps of:

-   -   (a) introducing a first feedstock and a second feedstock to the        first reaction zone, wherein the first feedstock comprises an        alkylatable aromatic compound(s), wherein the second feedstock        comprises an alkene and at least 1 mol. % alkane;    -   (b) contacting the first feedstock and the second feedstock with        a first catalyst in the first reaction zone to produce a first        effluent, the first reaction zone being maintained under        conditions such that the first reaction zone is predominately        liquid phase, wherein the first effluent comprises an alkylated        aromatic compound and alkane;    -   (c) cooling the first effluent without separation of the alkane        from the first effluent;    -   (d) supplying at least a portion of the cooled first effluent        and a third feedstock to the second reaction zone, wherein the        third feedstock comprises an alkene; and    -   (e) contacting the at least a portion of the cooled first        effluent and the third feedstock with a second catalyst in the        second reaction zone to produce a second effluent, the second        reaction zone being maintained under conditions such that the        second reaction zone is predominately liquid phase.

In another embodiment, the process comprises another step of separatingthe first and second effluents to recover the alkylated aromaticcompound. In yet another embodiment, the process comprises another stepof separating at least a portion of liquid at the bottom of a reactionzone prior to the liquid exiting for cooling. In yet another embodiment,the process comprises another step of feeding at least a portion ofvapor and/or liquid effluent at the bottom of a reaction zone prior tothe liquid exiting for cooling to a downstream reaction zone.

In yet another embodiment, the process comprises a further step ofcontacting the first feedstock and the fourth feedstock with analkylation catalyst in a by-passable pre-reactor upstream of thereactor, wherein the fourth feedstock comprises an alkene. In anotherembodiment, the process comprises a further step of contacting thesecond feedstock from the reactor under alkylation conditions with analkylation catalyst in a finishing-reactor downstream of the reactor.

In one aspect of the above embodiment, the first and second catalysts isa molecular sieve selected from the group consisting of MCM-22, MCM-36,MCM-49, MCM-56, beta zeolite, faujasite, mordenite, PSH-3, SSZ-25,ERB-1, ITQ-1, ITQ-2, zeolite Y, Ultrastable Y (USY), Dealuminized Y,rare earth exchanged Y (REY), ZSM-3, ZSM-4, ZSM-18, ZSM-20, or anycombination thereof. In a preferred embodiment, the first and secondcatalysts have at least one catalyst composition. In an alternativeembodiment, at least one reaction zone has a first catalyst compositionand at least another reaction zone has a second catalyst composition.

In yet another aspect of any one of the above embodiments, theconditions in steps (b) and (e) include a temperature of 100 to 285° C.(212 to 500° F.) and a pressure of 689 to 4601 kPa-a (100 to 667 psia).

In another embodiment of this invention, the second, the third, and thefourth feedstocks comprise a mixture of first alkene component and asecond alkene component. The first alkene component comprises 80 mol. %to 100 mol. % of the alkenes. The second alkene component comprises atleast 10 mol. % alkene. Preferably, the second alkene componentcomprises from 20 to 80 mol. % alkene.

In one aspect of any one of the above embodiments, the second, thethird, and the fourth feedstocks are made by 1) mixing the first alkenecomponent and the second alkene component; and 2) adjusting the mixedcomponent to the conditions of steps (b) and/or (e). In another aspectof any one of the above embodiments, the second feedstock is made by 1)adjusting the first alkene component and the second alkene componentseparately to the conditions of steps (b) or (e); and 2) mixing theconditioned first alkene component and the conditioned second alkenecomponent.

In an alternative embodiment of this invention, the above mentionedprocesses are suitable for retrofitting an existing ethylbenzene orcumene plant with a vapor, liquid, or mixed phase alkylation reactor. Inyet another embodiment of this invention, the above mentioned processesare suitable for retrofitting an existing AlCl₃ or BF₃ ethylbenzene orcumene plant.

In a preferred embodiment, the alkylated aromatic compound comprisesethylbenzene, the first feedstock comprises benzene, and the second, thethird and the fourth feedstocks comprise a mixture of ethylene, methane,and ethane.

In another preferred embodiment, the alkylated aromatic compoundcomprises cumene, the first feedstock comprises benzene, and the second,the third and the fourth feedstocks comprise a mixture of propylene,propane, methane, and ethane.

In yet another preferred embodiment, this invention relates to a processfor producing an alkylated aromatic compound in a reactor having aplurality of reaction zones including a first reaction zone and a secondreaction zone, the process comprises the steps of:

-   -   (a) introducing a first feedstock and a second feedstock to the        first reaction zone, wherein the first feedstock comprises an        alkylatable aromatic compound(s), wherein the second feedstock        comprises an alkene and at least 1 mol. % alkane;    -   (b) contacting the first feedstock and the second feedstock with        a first catalyst in the first reaction zone to produce a first        effluent, the first reaction zone being maintained under        conditions such that the first reaction zone is predominately        liquid phase, wherein the first effluent comprises an alkylated        aromatic compound, alkane, and polyalkylated aromatic        compound(s);    -   (c) cooling the first effluent without separation of the alkane        from the first effluent;    -   (d) supplying at least a portion of the cooled first effluent        and a third feedstock to the second reaction zone, wherein the        third feedstock comprises an alkene;    -   (e) contacting the at least a portion of the cooled first        effluent and the third feedstock with a second catalyst in the        second reaction zone to produce a second effluent, the second        zone being maintained under conditions such that the second        reaction zone is predominately liquid phase, wherein the second        effluent comprises the alkylated aromatic compound and the        polyalkylated aromatic compound(s);    -   (f) separating at least a portion the first and/or second        effluents to recover the polyalkylated aromatic compound(s) to        form a transalkylation feed stream; and    -   (g) contacting at least a portion of the transalkylation feed        stream with a fourth feedstock in the presence of a        transalkylation catalyst to produce a transalkylation effluent        under transalkylation conditions, wherein the fourth feedstock        comprises an alkylatable aromatic compound(s), the        transalkylation effluent which comprises the alkylated aromatic        compound.

The above embodiment may further comprise the step of separating thetransalkylation effluent to recover the alkylated aromatic compound.

In one aspect of the above embodiments, the transalkylation catalyst isa molecular sieve selected from the group consisting of MCM-22, MCM-36,MCM-49 and MCM-56, beta zeolite, faujasite, mordenite, PSH-3, SSZ-25,ERB-1, ITQ-1, ITQ-2, zeolite Y, Ultrastable Y (USY), Dealuminized Y,rare earth exchanged Y (REY), ZSM-3, ZSM-4, ZSM-18, ZSM-20, or anycombination thereof. In another aspect of the above embodiments, thetransalkylation conditions of the transalkylation zone includetemperature of 100 to 450° C. (212 to 842° F.) and a pressure of 689 to4601 kPa-a (100 to 667 psia).

In one preferred embodiment, the alkylated aromatic compound comprisesethylbenzene. In another preferred embodiment, the alkylated aromaticcompound comprises cumene.

DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are flow diagrams of a process for producing ethylbenzenein accordance with the examples of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Detail Description ofthe Process

Referring to one embodiment of this invention as illustrated in FIG. 1,a reactor 20 has three reaction zones, a first reaction zone 35, asecond reaction zone 47, and a third reaction zone 59. A first feedstockcomprising an alkylatable aromatic compound, is fed to a by-passablereactive guard bed 25 via line 7 and further via line 9. A first alkenecomponent comprising a concentrate alkene via line 1 is premixed with asecond alkene component comprising dilute alkene via line 3 to form asecond feedstock comprising an alkene and at least 1 mol. % alkane. Thesecond feedstock is fed to the by-passable reactive guard bed 25 vialine 13. A portion of both the first feedstock and the second feedstockmay by-pass the reactive guard bed 25 via line 19. The reactive guardbed 25 may contain alkylation catalyst, e.g., MCM-22. The reactive guardbed 25 typically operates at or near 100% alkene conversion, but mayoperate at lower conversion so that the effluent of the reactive guardbed 25 leaving via line 27 is composed of alkylated aromatic compound(e.g., ethylbenzene or cumene), any unreacted alkene (e.g., ethylene),unreacted alkylatable aromatic compound (e.g., benzene), and unreactedlight impurities (e.g., hydrogen, nitrogen, methane, and ethane). Thereactive guard bed effluent in line 27 is further combined with thestream in line 19 and then passed to a heat exchanger 21 via line 23. Aneffluent of the heat exchanger 21 is fed to the reaction zone 35 vialine 33. Additional second feedstock is fed to the reaction zone 35 vialine 31. The conditions (temperature and pressure) of the reaction zone35 is such that the mixed feedstocks is in predominantly liquid phase.The reaction zone 35 is packed with an alkylation catalyst, e.g.,MCM-22. The unreacted alkylatable aromatic compound in the stream ofline 33 is alkylated with the alkene in the additional second feedstockin line 31. An effluent from the reaction zone 35 is withdrawn from thereaction zone 35 via line 37. The conditions of the reaction zone 35 aresuch that the reaction zone 35 is maintained in predominantly liquidphase. The alkylation catalyst of the reaction zone 35 is typicallyoperated at or near to 100% ethylene conversion.

An effluent from the reaction zone 35 is withdrawn from the reactionzone 35 via line 37, passed to a heat exchanger 39 prior to injectioninto the reaction zone 47 via line 41. A portion of the effluent fromthe reaction zone 35 may by-pass the heat exchanger 39 via line 45.Additional second feedstock is fed to the reaction zone 47 via line 43.The conditions of the reaction zone 47 are such that the reaction zone47 is maintained in predominantly liquid phase. The alkylation catalystof the reaction zone 47 is typically operated at or near to 100%ethylene conversion. An effluent from the reaction zone 47 is withdrawnfrom reaction zone 47 via line 49, passed to the heat exchanger 51 priorto injection in the reaction zone 59 via line 53. Again, a portion ofthe effluent from the reaction zone 47 may by-pass the heat exchanger 51via line 57 and additional second feedstock is fed to reaction zone 59via line 55. The conditions of the reaction zone 59 are such that thereaction zone 59 is maintained in predominantly liquid phase. Thealkylation catalyst of the reaction zone 59 is typically operated at ornear to 100% ethylene conversion. An effluent from the reaction zone 59is withdrawn from reaction zone 59 via line 61, passed to the heatexchanger 62 prior to injection into a by-passable finishing-reactor 67via line 64. Again, a portion of the effluent from the reaction zone 59may by-pass the heat exchanger 62 via line 66 and additional secondfeedstock is fed to the by-passable finishing-reactor 67 via line 63.The conditions of the by-passable finishing-reactor 67 are such that theby-passable finishing-reactor 67 is maintained in predominantly liquidphase. A portion of the feed to the by-passable finishing-reactor 67 mayby-pass the by-passable finishing-reactor 67 via line 71. The alkylationcatalyst of the by-passable finishing-reactor 67 is typically operatedat or near to 100% ethylene conversion.

The effluent of line 69 from the reaction zone 67 combining with theby-pass stream via line 71 leaves by-passable finishing-reactor 67 vialine 73. The stream in line 73 containing the desired alkylated aromaticeffluent as well as any unreacted alkene, unreacted alkylatable aromaticcompound, polyalkylated aromatic compounds, methane, and ethane furthervia line 75 is fed to a separation block 77. The unreacted benzene isseparated and withdrawn via line 97 recycling to the reaction zones. Anoverhead effluent of the separation block 77 containing benzene andlights (e.g., ethane, and methane), is withdrawn from separation block77 via line 79 to a striper 81 where benzene is striped and withdrawnvia line 87. The lights are removed via line 83. Heavies comprising thepolyalkylated aromatic compounds separated from the separation block 77are withdrawn from the separation block 77 via line 89 to a furtherseparation block 91 where the polyalkylated aromatic compounds areseparated and withdrawn via line 85 to the striper 81, optionallycombined with additional polyalkylated aromatic compounds via line 82.The combined polyalkylated aromatic compounds strips the benzenecomponent in the striper 81. A bottom stream of the striper 81 iswithdrawn via line 87 further combines with additional first feedstockvia line 99. The combined stream is fed to a transalkylation reactor 103via line 101. The transalkylation reactors 103 is operated underconditions such that 20-100 wt. %, preferably 40 to 80 wt. %, of thepolyalkylated aromatic compounds in the stream of line 101 are convertedto alkylated aromatic compound. An effluent in line 105 from thetransalkylation reactors is combined with the effluent of line 73 fromthe by-passable finishing reactor 67 as it passes to the separationblock 77. The alkylated aromatic compound is separated as a effluentstream withdrawn via line 93.

Referring to another embodiment of this invention as illustrated in FIG.2, a reactor 221 has three reaction zones, a reaction zone 235, areaction zone 247, and a reaction zone 259. A first feedstock comprisingalkylatable aromatic compound is fed to a by-passable reactive guard bed225 via line 207 and further via line 209. A second feedstock comprisingalkene and at least 1 mol. % of alkane is fed to a reactive guard bed225 via line 213. The second feedstock is a mixture of a first alkenecomponent comprising a concentrate alkene and/or a second alkenecomponent comprising dilute alkene. A portion of both the firstfeedstock and the second feedstock may by-pass the reactive guard bed225 via line 219. The reactive guard bed 225 may contain alkylationcatalyst, e.g., MCM-22. The reactive guard bed 225 typically operates ator near 100% alkene conversion, but may operate at lower conversion sothat an effluent of line 227 leaving the reactive guard bed 225 iscomposed of alkylated aromatic compound (e.g., ethylbenzene or cumene),any unreacted alkene (e.g., ethylene), unreacted alkylatable aromaticcompound (e.g., benzene), and unreacted light impurities (e.g.,hydrogen, nitrogen, methane, and ethane). The reactive guard bedeffluent in line 227 is further combined with the stream of line 219 andthen passed to a heat exchanger 221 via line 223 before passing to thereaction zone 235 via line 233. Additional second feedstock is fed tothe reaction zone 235 via line 231. The addition second feedstock is amixture of a first alkene component comprising a concentrate ethyleneand/or a second alkene component comprising dilute alkene, which may bedifferent in composition from the second feedstock feeding through line213. The conditions (temperature and pressure) of the reaction zone 235is such that the mixed feedstocks is in predominantly liquid phase. Thereaction zone 235 is packed with an alkylation catalyst, e.g., MCM-22.The unreacted alkylatable aromatic compound in feed of line 233 isalkylated with the alkene in the additional second feedstock via line231. An effluent from the reaction zone 235 is withdrawn from thereaction zone 235 via line 237. The alkylation catalyst of the reactionzone 235 is typically operated at or near to 100% ethylene conversion.

The effluent from the reaction zone 235 is withdrawn from the reactionzone 235 via line 237, passed to a heat exchanger 239 prior to injectionin the reaction zone 247 via line 241. A portion of the effluent fromthe reaction zone 235 may by-pass the heat exchanger 239 via line 245.Another additional second feedstock is fed to the reaction zone 247 vialine 243. The conditions of the reaction zone 247 are such that thereaction zone 247 is maintained in predominantly liquid phase. Thealkylation catalyst of the reaction zone 247 is typically operated at ornear to 100% ethylene conversion. An effluent from the reaction zone 247is withdrawn from reaction zone 247 via line 249, passed to a heatexchanger 251 prior to injection in the reaction zone 259 via line 253.Again, a portion of the effluent from the reaction zone 247 may by-passthe heat exchanger 251 via line 257 and additional second feedstock isfed to reaction zone 259 via line 255. The conditions of the reactionzone 259 are such that the reaction zone 259 is maintained inpredominantly liquid phase. The alkylation catalyst of the reaction zone259 is typically operated at or near to 100% ethylene conversion. Aneffluent from the reaction zone 259 is withdrawn from reaction zone 259via line 261, passed to the heat exchanger 262 prior to injection in aby-passable finishing-reactor 267 via line 264. Again, a portion of theeffluent from the reaction zone 259 may by-pass the heat exchanger 262via line 266 and additional second feedstock is fed to the by-passablefinishing-reactor 267 via line 263. The conditions of the by-passablefinishing-reactor 267 are such that the by-passable finishing-reactor267 is maintained in predominantly liquid phase. A portion of the feedto the by-passable finishing-reactor 267 may by-pass the by-passablefinishing-reactor 267 via line 271. The alkylation catalyst of theby-passable finishing-reactor 267 is typically operated at or near to100% ethylene conversion.

An effluent in line 269 from the reaction zone 269 combining with theby-pass stream via line 271 which contains the desired alkylatedaromatic product as well as any unreacted alkene, unreacted alkylatablearomatic compound, polyalkylated aromatic compounds, methane, ethane.The combined stream is withdrawn via line 273 and further via line 290feeding to a separation block 277. An overhead effluent of theseparation block 277 containing benzene and lights (e.g., ethane, andmethane), is withdrawn from separation block 277 via line 279 to astriper 281 where benzene is striped and withdrawn via line 287. Thelights are removed via line 283. Heavies comprising the unreactedbenzene and the polyalkylated aromatic compounds separated from theseparation block 277 are withdrawn from the separation block 277 vialine 289 to a separation block 296 where the unreacted benzene isseparated as an overhead effluent and recycled via line 297. A bottomstream comprising polyalkylated aromatic compounds is withdrawn via line298 to a further separation block 291. The polyalkylated aromaticcompounds are separated and withdrawn via line 285 to a striper 281,optionally combined with additional polyalkylated aromatic compounds vialine 282. The combined polyalkylated aromatic compounds strip thebenzene component in the striper 281 and withdrawn via line 287 furthercombines with additional first feedstock via line 299. The combinedstream is fed to a transalkylation reactor 303 via line 301. Thetransalkylation reactors 303 is operated under conditions such that20-100 wt. %, preferably 40 to 80 wt. %, of the polyalkylated aromaticcompounds are converted to alkylated aromatic compound. The effluent ofline 305 from the transalkylation reactors is combined with the effluentof line 273 from the reactor 267 as it passes to the separation block277. The alkylated aromatic compound is separated as a effluent streamwithdrawn via line 293.

Feedstocks

The first feedstock comprises an alkylatable aromatic compound. The term“aromatic” in reference to the alkylatable compounds which are usefulherein is to be understood in accordance with its art-recognized scopewhich includes alkyl substituted and unsubstituted mono- and polynuclearcompounds. Compounds of an aromatic character, which possess aheteroatom are also useful provided they do not act as catalyst poisonsunder the reaction conditions selected.

Substituted aromatic compounds which can be alkylated herein mustpossess at least one hydrogen atom directly bonded to the aromaticnucleus. The aromatic rings can be substituted with one or more alkyl,aryl, alkaryl, alkoxy, aryloxy, cycloalkyl, halide, and/or other groupswhich do not interfere with the alkylation reaction.

Suitable aromatic hydrocarbons include benzene, naphthalene, anthracene,naphthacene, perylene, coronene, and phenanthrene, with benzene beingpreferred.

Suitable alkyl substituted aromatic compounds include toluene, xylene,isopropylbenzene, normal propylbenzene, alpha-methylnaphthalene,ethylbenzene, mesitylene, durene, cymenes, butylbenzene, pseudocumene,o-diethylbenzene, m-diethylbenzene, p-diethylbenzene, isoamylbenzene,isohexylbenzene, pentaethylbenzene, pentamethylbenzene;1,2,3,4-tetraethylbenzene; 1,2,3,5-tetramethylbenzene;1,2,4-triethylbenzene; 1,2,3-trimethylbenzene, m-butyltoluene;p-butyltoluene; 3,5-diethyltoluene; o-ethyltoluene; p-ethyltoluene;m-propyltoluene; 4-ethyl-m-xylene; dimethylnaphthalenes;ethylnaphthalene; 2,3-dimethylanthracene; 9-ethylanthracene;2-methylanthracene; o-methylanthracene; 9,10-dimethylphenanthrene; and3-methyl-phenanthrene. Higher molecular weight alkylaromatichydrocarbons can also be used as starting materials and include aromatichydrocarbons such as are produced by the alkylation of aromatichydrocarbons with olefin oligomers. Such products are frequentlyreferred to in the art as alkylate and include hexylbenzene,nonylbenzene, dodecylbenzene, pentadecylbenzene, hexyltoluene,nonyltoluene, dodecyltoluene, pentadecytoluene, etc. Very often alkylateis obtained as a high boiling fraction in which the alkyl group attachedto the aromatic nucleus varies in size from about C6 to about C12.

Reformate containing substantial quantities of benzene, toluene and/orxylene constitutes a particularly useful feed for the alkylation processof this invention. Although the process is particularly directed to theproduction of ethylbenzene from polymer grade and dilute ethylene, it isequally applicable to the production of other C₇-C₂₀ alkylaromaticcompounds, such as cumene, as well as C₆+ alkylaromatics, such as C₈-C₁₆linear and near linear alkylbenzenes.

The second feedstock comprises an alkene compound. Typically, the secondfeedstock includes a concentrated alkene feedstock (e.g., grade alkene)and a dilute alkene feedstock (e.g., catalytic cracking off-gas).

The concentrated alkene alkylating agent of the feedstock useful in theprocess of this invention includes an alkene feed comprised of at least80 mol. % of the alkene and preferably at least 99 mol. % to 100 mol. %.

The dilute alkylating agent of the feedstock useful in the process ofthis invention includes a dilute alkene feed which contains at least onealkene and optionally at least one alkane. For example, where the alkeneis ethylene, the alkane may be ethane and/or methane. Typically, thedilute alkene feed comprises at least 10 mol. % of the alkene,preferably from 20 to 80 mol. % of the alkene. One particularly usefulfeed is the dilute ethylene stream obtained as an off gas from the fluidcatalytic cracking unit of a petroleum refinery.

In one embodiment of the invention, the second feedstock includes aconcentrated alkene feedstock only. In another embodiment of theinvention, the second feedstock includes a dilute alkene feedstock only.In yet another embodiment of the invention, the second feedstock is amixture of a plurality of feedstocks having alkene and alkane e.g., atleast one concentrated alkene feedstock having at least 80 mol. % alkeneand at least one dilute alkene feedstock having 10-80 mol. % alkene.

In one embodiment, a plurality of feedstocks having alkene may bepre-mixed before being brought to the suitable conditions for alkylationreaction. In another embodiment of the invention, a plurality offeedstocks having alkene may be separately conditioned to the suitableconditions before feeding to the reaction zone(s). The relative amountof each separately conditioned alkene feedstock to be mixed and fed tothe reaction zone(s) is varied based on the reaction conditions,catalyst (activity and amount), and space hour velocity. In oneembodiment, the first few reaction zones of the reactor are fed with asecond feedstock having higher alkene content than that of the secondfeedstock for the second few reaction zones.

Alkylation and Transalkylation Reactions

The alkylation reaction zone is operated in a predominantly liquidphase. In one embodiment, the inlet conditions of the inlet portion ofthe reaction zone include a temperature of 100 to 260° C. (212 to 500°F.) and a pressure of 689 to 4601 kPa-a (100 to 667 psia), preferably, apressure of 1500 to 3500 kPa-a (218 to 508 psia). The conditions of thedownstream reaction zone include a temperature of 150 to 285° C. (302 to545° F.) and a pressure of 689 to 4601 kPa-a (100 to 667 psia),preferably, a pressure of 1500 to 3000 kPa-a (218 to 435 psia), a WHSVbased on alkene for overall reactor of 0.1 to 10 h⁻¹, preferably, 0.2 to2 h⁻¹, more preferably, 0.5 to 1 h⁻¹, or a WHSV based on both alkene andbenzene for overall reactor of 10 to 100 h⁻¹, preferably, 20 to 50 h⁻¹.Typically temperature is higher in the downstream portion of thereaction zone than the inlet portion of the reaction zone due to theexothermic nature of the alkylation reaction. The alkylatable aromaticcompound is alkylated with the alkene in the second feedstock in thepresence of an alkylation catalyst in a reactor having at least tworeaction zones. The reaction zones are typically located in a singlereactor vessel, but may include a reaction zone including an alkylationcatalyst bed, located in separate vessel which may be a by-passable andwhich may operate as a reactive guard bed. The catalyst composition usedin the reactive guard bed may be different from the catalyst compositionused in the alkylation reactor. The catalyst composition used in thereactive guard bed may have multiple catalyst compositions. At least thefirst alkylation reaction zone, and normally each alkylation reactionzone, is operated under conditions effective to cause alkylation of thealkylatable aromatic compound with the alkene component of the secondfeedstock in the presence of a alkylation catalyst.

The effluent from the first alkylation reaction zone (first product)comprises the desired alkylated aromatic product, unreacted alkylatablearomatic compound, any unreacted alkene (alkene conversion is expectedto be at least 90 mol. %, preferably, about 98-99.9999 mol. %) and thealkane component and the other impurities. The temperature, pressure,and composition of the effluent is such that the effluent is maintainedin predominantly liquid phase when the effluent exits the reaction zone.The temperature of the effluent is typically higher than the temperatureof the feed because the alkylation reaction is generally exothermic. Tomaintain the next reaction zone in liquid-phase, the effluent istypically removed from the first reaction zone and cooled. The effluentcan also be cooled by internal cooling system between reaction zones.The cooling step does not remove any unreacted alkane except to theextent of leak or loss due to equipment and operation. At least aportion of the effluent is fed to the second alkylation reaction zonewhere additional second feedstock is added for reaction with theunreacted alkylatable aromatic compound with a second catalyst. Wherethe process employs more than two alkylation reaction zones, theeffluent from each zone is fed to the next zone with additional secondfeedstock. The effluent from the second reaction zone contains moreunreacted alkane and more alkylated aromatic compound. Furthermore, atleast a portion the effluent from the second alkylation reaction zoneand/or other zones can be fed directly or indirectly to atransalkylation unit.

The term “predominately liquid phase” used herein is understood ashaving at least 95 wt. % liquid phase, preferably, 98 wt. %, morepreferably, 99 wt. %, and most preferably, 99.5 wt. %.

In addition to, and upstream of, the alkylation zones, the alkylationreaction system may also include a by-passable reactive guard bednormally located in a pre-reactor separate from the remainder of thealkylation reactor. The reactive guard bed may also loaded withalkylation catalyst, which may be the same or different from thecatalyst used in the multi-stage alkylation reaction system. Thereactive guard bed is maintained from under ambient or up to alkylationconditions. At least a portion of alkylatable aromatic compound andtypically at least a portion of the second feedstock are passed throughthe reactive guard bed prior to entry into the first reaction zone ofthe alkylation reaction zones in the reactor. The reactive guard bed notonly serves to affect the desired alkylation reaction but is also usedto remove any reactive impurities in the feeds, such as nitrogencompounds, which could otherwise poison the remainder of the alkylationcatalyst. The catalyst in the reactive guard bed is therefore subject tomore frequent regeneration and/or replacement than the remainder of thealkylation catalyst and hence the guard bed is normally provided with aby-pass circuit so that the alkylation feedstock can be fed directly tothe series connected alkylation reaction zones in the reactor when theguard bed is out of service. The reactive guard bed operates inpredominantly liquid phase and in co-current upflow or downflowoperation.

The alkylation reactor used in the process of the present invention isnormally operated so as to achieve essentially complete conversion ofthe alkene in the second feedstock. However, for some applications, itmay be desirable to operate at below 100% alkene conversion. Theemployment a separate finishing reactor downstream of the multi-zonesalkylation reactor may be desirable under certain conditions. Thefinishing reactor would also contain alkylation catalyst, which could bethe same or different from the catalyst used in the alkylation reactorand could be operated under predominantly liquid phase alkylationconditions.

The alkylation reactor used in the process of the present invention ishighly selective to the desired alkylated product, such as ethylbenzene,but normally produces at least some polyalkylated species. Thus theeffluent from the final alkylation reaction zone is supplied to atransalkylation reactor which is normally separate from the alkylationreactor. The transalkylation reactor produces additional alkylatedproduct by reacting the polyalkylated species with aromatic compound.

Particular conditions for carrying out the liquid phase alkylation ofbenzene with ethylene may a temperature of from about 120 to 285° C.,preferably, a temperature of from about 150 to 260° C., a pressure of689 to 4601 kPa-a (100 to 667 psia), preferably, a pressure of 1500 to3000 kPa-a (218 to 435 psia), a WHSV based on ethylene for overallreactor of 0.1 to 10 h⁻¹, preferably, 0.2 to 2 h⁻¹, more preferably, 0.5to 1 h⁻¹, or a WHSV based on both ethylene and benzene for overallreactor of 10 to 100 h⁻¹, preferably, 20 to 50 h⁻¹, and a mole ratio ofbenzene to ethylene from about 1 to about 10.

Particular conditions for carrying out the predominantly liquid phasealkylation of benzene with propylene may include a temperature of fromabout 80 to 160° C., a pressure of about 680 to about 4800 kPa-a;preferably from about 100 to 140° C. and pressure of about 2000 to 3000kPa-a, a WHSV based on propylene of from about 0.1 about 10 hr⁻¹, and amole ratio of benzene to ethylene from about 1 to about 10.

Where the alkylation system includes a reactive guard bed, it isoperated under at least partial liquid phase conditions. The guard bedwill preferably operate at a temperature of from about 120 to 285° C.,preferably, a temperature of from about 150 to 260° C., a pressure of689 to 4601 kPa-a (100 to 667 psia), preferably, a pressure of 1500 to3000 kPa-a (218 to 435 psia), a WHSV based on ethylene for overallreactor of 0.1 to 10 h⁻¹, preferably, 0.2 to 2 h⁻¹, more preferably, 0.5to 1 h⁻¹, or a WHSV based on both ethylene and benzene for overallreactor of 10 to 100 h⁻¹, preferably, 20 to 50 h⁻¹, and a mole ratio ofbenzene to ethylene from about 1 to about 10.

The polyalkylated aromatic compounds in the effluents may be separatedfor transalkylation with alkylatable aromatic compound(s). The alkylatedaromatic compound is made by transalkylation between polyalkylatedaromatic compounds and the alkylatable aromatic compound.

The transalkylation reaction takes place under predominantly liquidphase conditions. Particular conditions for carrying out thepredominantly liquid phase transalkylation of polyethylbenzene(s) withbenzene may include a temperature of from about 150° to about 260° C., apressure of 696 to 4137 kPa-a (101 to 600 psia), a WHSV based on theweight of the polyethylbenzene(s) feed to the reaction zone of fromabout 0.5 to about 100 hr⁻¹ and a mole ratio of benzene topolyethylbenzene(s) of from 1:1 to 30:1, preferably, 1:1 to 10:1, morepreferably, 1:1 to 5:1.

In another embodiment, the transalkylation reaction takes place undervapor phase conditions. Particular conditions for carrying out the vaporphase transalkylation of polyethylbenzenes with benzene may include atemperature of from about 350 to about 450° C., a pressure of 696 to1601 kPa-a (101 to 232 psia), a WHSV based on the weight of thepolyethylbenzene(s) feed to the reaction zone of from about 0.5 to about20 hr⁻¹, preferably, from about 1 to about 10 hr⁻¹, and a mole ratio ofbenzene to polyethylbenzene(s) of from 1:1 to 5:1, preferably, 2:1 to3:1.

In an alternative embodiment of this invention, the above mentionedprocesses are suitable for retrofitting an existing ethylbenzene orcumene plant with a vapor, liquid, or mixed phase alkylation reactor. Inparticular, the process of this invention may be used to retrofit anexisting ethylbenzene or cumene plant using polymer grade or chemicalgrade ethylene or propylene with minimum amount of new equipments, suchas, extra compressors for the second feedstock, extra-separation columnfor light gas and aromatics, and other equipment.

Catalysts

The alkylation and transalkylation catalyst used in the process of theinvention is not critical but normally comprises at least one of MCM-22,MCM-49, MCM-36, MCM-56, beta zeolite, faujasite, mordenite, PSH-3,SSZ-25, ERB-1, ITQ-1, ITQ-2 and optionally SAPO molecular sieves (e.g.,SAPO-34 and SAPO-41).

MCM-22 and its use to catalyze the synthesis of alkylaromatics,including ethylbenzene, is described in U.S. Pat. Nos. 4,992,606;5,077,445; and 5,334,795. PSH-3 is described in U.S. Pat. No. 4,439,409.SSZ-25 and its use in aromatics alkylation are described in U.S. Pat.No. 5,149,894. ERB-1 is described in European Patent No. 0293032. ITQ-1is described in U.S. Pat. No. 6,077,498. ITQ-2 is described inInternational Patent Publication No. WO97/17290 and WO01/21562. MCM-36is described in U.S. Pat. Nos. 5,250,277 and 5,292,698. U.S. Pat. No.5,258,565 describes the synthesis of alkylaromatics, includingethylbenzene, using a catalyst comprising MCM-36. MCM-49 is described inU.S. Pat. No. 5,236,575. The use of MCM-49 to catalyze the synthesis ofalkylaromatics, including ethylbenzene, is described in U.S. Pat. Nos.5,508,065 and 5,371,310. MCM-56 is described in U.S. Pat. No. 5,362,697.The use of MCM-56 to catalyze the synthesis of alkylaromatics includingethylbenzene is described in U.S. Pat. Nos. 5,557,024 and 5,453,554. Theentire contents of all the above patent specifications are incorporatedherein by reference.

Alternatively, the alkylation and transalkylation catalyst can comprisea medium pore molecular sieve having a Constraint Index of 2-12 (asdefined in U.S. Pat. No. 4,016,218), including ZSM-5, ZSM-11, ZSM-12,ZSM-22, ZSM-23, ZSM-35, and ZSM-48. ZSM-5 is described in detail in U.S.Pat. No. 3,702,886 and Re. 29,948. ZSM-11 is described in detail in U.S.Pat. No. 3,709,979. ZSM-12 is described in U.S. Pat. No. 3,832,449.ZSM-22 is described in U.S. Pat. No. 4,556,477. ZSM-23 is described inU.S. Pat. No. 4,076,842. ZSM-35 is described in U.S. Pat. No. 4,016,245.ZSM-48 is more particularly described in U.S. Pat. No. 4,234,231. Theentire contents of all the above patent specifications are incorporatedherein by reference.

As a further alternative, the alkylation and transalkylation catalystcan comprise a large pore molecular sieve having a Constraint Index lessthan 2. Suitable large pore molecular sieves include zeolite beta,zeolite Y, Ultrastable Y (USY), Dealuminized Y (Deal Y), mordenite,ZSM-3, ZSM-4, ZSM-18, and ZSM-20. Zeolite ZSM-14 is described in U.S.Pat. No. 3,923,636. Zeolite ZSM-20 is described in U.S. Pat. No.3,972,983. Zeolite Beta is described in U.S. Pat. No. 3,308,069, and Re.No. 28,341. Low sodium Ultrastable Y molecular sieve (USY) is describedin U.S. Pat. Nos. 3,293,192 and 3,449,070. Dealuminized Y zeolite (DealY) may be prepared by the method found in U.S. Pat. No. 3,442,795.Zeolite UHP-Y is described in U.S. Pat. No. 4,401,556. Rare earthexchanged Y (REY) is described in U.S. Pat. No. 3,524,820. Mordenite isa naturally occurring material but is also available in synthetic forms,such as TEA-mordenite (i.e., synthetic mordenite prepared from areaction mixture comprising a tetraethylammonium directing agent).TEA-mordenite is disclosed in U.S. Pat. Nos. 3,766,093 and 3,894,104.The entire contents of all the above patent specifications areincorporated herein by reference.

The same catalyst may be used in both the transalkylation zone and thealkylation zones of the present invention. Preferably, however,catalysts are chosen for the different alkylation zones and thetransalkylation zone, so as to be tailored for the particular reactionscatalyzed therein. In one embodiment of the present invention, astandard activity catalyst for example, 50% zeolite and 50% binder isused in the higher temperature alkylation catalyst beds and a higheractivity catalyst for example, 75% zeolite and 25% binder is used in thelower temperature alkylation catalyst beds, while suitabletransalkylation catalyst is used in the transalkylation zone. In such anembodiment, any finishing reactor zone could include a MCM-22 catalystbed for predominantly liquid phase operation.

In the process of the invention, the alkylation reaction in at least thefirst, and normally in each, of the alkylation reaction zones takesplace under predominantly liquid phase conditions, such that thealkylatable aromatic compound is in the predominantly liquid phase.

The invention will be more particularly described with reference to thefollowing Examples.

EXAMPLES Example 1 Liquid Phase Alkylation

The following example is a computer simulation of benzene ethylationwith ethylene in liquid phase. Simulation results were obtained using aproprietary numerical software package. Vapor-liquid equilibrium wascalculated, the Soave-Redlich-Kwong Equation-of-State (with optimizedinteraction coefficients).

The feed to each catalyst bed is characterized by a B/E ratio (Benzeneto Ethylene molar ratio) and an E/E ratio (Ethylene to Ethane molarratio). The very high E/E ratio is an indication of an ethylenefeedstock with a polymer grade ethylene purity. This case is configuredto operate in the liquid phase with high E/E ratio. The temperatures andpressures of the feed and effluent streams to each bed are sufficient toallow all liquid phase operation in the catalyst bed. The results of thesimulation are shown in Table 1.

TABLE 1 Ethylene EB conversion cumulative B/E E/E Fraction T P (%) yield(mol. %) ratio ratio Liquid (° C.) (kPa-a) Bed 1 Feed — 21.0 261 1 222.24270 Effluent 100 4.8 — — 1 246.3 4220 Bed 2 Feed — 20.0 229 1 242.64210 Effluent 100 9.0 — — 1 265 4165 Bed 3 Feed — 19.1 218 1 222.9 4035Effluent 100 13.0 — — 1 246.4 3980 Bed 4 Feed — 18.1 183 1 242.9 3980Effluent 100 16.9 — — 1 264.9 3915 Bed 5 Feed — 17.2 166 1 223.5 3715Effluent 100 20.6 — — 1 246.4 3660 Bed 6 Feed — 16.3 152 1 243.1 3660Effluent 100 24.1 — — 1 264.7 3590

Example 2 Liquid Phase Alkylation with Mixed Ethylene Feedstocks

The following example is a computer simulation ofmixed-phase/liquid-phase benzene ethylation with mixed ethylenefeedstocks by the process of the present invention. The case isconfigured to operate in liquid-phase. The temperatures and pressures ofthe feed and effluent streams to each bed are sufficient to allowliquid-phase operation in the catalyst bed. The results of thesimulation are shown in Table 2.

Option 1 for modification of the plant after addition of dilute ethylenehas the characteristics shown in Table 2. The feed to each catalyst bedis characterized by a B/E ratio (Benzene to Ethylene molar ratio) and anE/E ratio (Ethylene to Ethane molar ratio). The E/E ratio issignificantly lower than in the base-case (example 1) indicating agreater concentration of ethane and representative of dilute ethylenestreams and/or mixed chemical/polymer grade and dilute ethylene streams.The entire contents of this dilute ethylene configuration operates inthe liquid phase (after sufficient residence time is allowed downstreamof the ethylene/ethane injectors to allow the ethylene/ethane tocompletely dissolve in the liquid. The Temperatures and Pressures of thefeed and effluent streams to each bed are sufficient to allow all liquidphase operation in the catalyst bed.

The E/E ratio decreases from bed to bed in the reactor because while theethylene is consumed, the ethane builds up in the reactor. In addition,the average temperature of each pair of catalyst beds decreases down thelength of the reactor to compensate for the ethane build-up and reducedpressure, due to pressure drop across the catalyst beds. In this way, atotal liquid phase is maintained even in the presence of significantamounts of ethane, which, if maintained at base-case conditions, wouldcause the reaction mixture to be in a mixed-phase (liquid/vapor) state.

TABLE 2 Ethylene EB conversion cumulative B/E E/E Fraction T P (%) yield(%) ratio ratio Liquid (° C.) (kPa-a) Bed 1 Feed 15.9 4.5 1 225.7 4270Effluent 100 6 1 256.3 4220 Bed 2 Feed 36.5 3.2 1 253.2 4210 Effluent100 8.2 1 264.8 4165 Bed 3 Feed 13.6 2.1 1 179.9 3925 Effluent 100 13.51 214.9 3870 Bed 4 Feed 17.0 1.2 1 211.8 3870 Effluent 100 17.2 1 235.83805 Bed 5 Feed 14.5 1.0 1 180.4 3635 Effluent 100 21 1 208.1 100 Bed 6Feed 31.2 0.42 1 206.9 3580 Effluent 100 22.5 1 218.5 3510

Example 3 Liquid Phase Alkylation with Mixed Ethylene Feedstocks

Option 2 for modification of the plant after addition of dilute ethylenehas the characteristics shown in Table 3. The feed to each catalyst bedis characterized by a B/E ratio (Benzene to Ethylene molar ratio) and anE/E ratio (Ethylene to Ethane molar ratio). The E/E ratio issignificantly lower than in the base-case (example 1) indicating agreater concentration of ethane and representative of dilute ethylenestreams and/or mixed chemical/polymer grade and dilute ethylene streams.The entire contents of this dilute ethylene configuration operates inthe liquid phase (after sufficient residence time is allowed downstreamof the ethylene/ethane injectors to allow the ethylene/ethane tocompletely dissolve in the liquid. The Temperatures and Pressures of thefeed and effluent streams to each bed are sufficient to allow all liquidphase operation in the catalyst bed.

Similarly to example 2, the E/E ratio decreases from bed to bed in thereactor because while the ethylene is consumed, the ethane builds up inthe reactor. In addition, the average temperature of each pair ofcatalyst beds decreases down the length of the reactor to compensate forthe ethane build-up and reduced pressure, due to pressure drop acrossthe catalyst beds. In this way, a total liquid phase is maintained evenin the presence of significant amounts of ethane, which, if maintainedat base-case conditions, would cause the reaction mixture to be in amixed-phase (liquid/vapor) state.

Dissimilar to example 2, the E/E ratio of the beds nearest the inlet issignificantly larger than the E/E ratio of those same beds in example 2.This indicates that more chemical/polymer grade ethylene is introducedin the inlet beds and more dilute ethylene feed is introduced in theoutlet beds. Consistent with this, the temperature of beds 2 & 4 inparticular are much higher than the temperature of these same beds inexample 2. Catalyst beds 1 & 2 tend to be close in temperature in bothexample 2 and example 3 because the total amount of C2 (ethylene andethane).

TABLE 3 Ethylene EB conversion cumulative B/E E/E Fraction T P (%) yield(%) ratio ratio Liquid (° C.) (kPa-a) Bed 1 Feed 15.1 15.0 1 214.2 4320Effluent 100 6.4 1 247.7 4270 Bed 2 Feed 20.9 6.7 1 243.8 4210 Effluent100 10.2 1 264.7 4165 Bed 3 Feed 14.6 6.4 1 222 4035 Effluent 100 15.2 1251.6 3980 Bed 4 Feed 21.0 3.5 1 248.3 3980 Effluent 100 18.3 1 266.33915 Bed 5 Feed 14.4 1.2 1 179.6 3685 Effluent 100 21.5 1 207.3 3630 Bed6 Feed 41.9 0.31 1 206 3630 Effluent 100 22.5 1 214.5 3560

All patents, patent applications, test procedures, priority documents,articles, publications, manuals, and other documents cited herein arefully incorporated by reference to the extent such disclosure is notinconsistent with this invention and for all jurisdictions in which suchincorporation is permitted.

When numerical lower limits and numerical upper limits are listedherein, ranges from any lower limit to any upper limit are contemplated.

While the illustrative embodiments of the invention have been describedwith particularity, it will be understood that various othermodifications will be apparent to and can be readily made by thoseskilled in the art without departing from the spirit and scope of theinvention. Accordingly, it is not intended that the scope of the claimsappended hereto be limited to the examples and descriptions set forthherein but rather that the claims be construed as encompassing all thefeatures of patentable novelty which reside in the present invention,including all features which would be treated as equivalents thereof bythose skilled in the art to which the invention pertains.

1. A process for producing an alkylated aromatic compound in a reactorhaving a plurality of reaction zones including a first reaction zone anda second reaction zone, said process comprising the steps of: (a)introducing a first feedstock and a second feedstock to said firstreaction zone, wherein said first feedstock comprises an alkylatablearomatic compound(s), wherein said second feedstock comprises an alkeneand at least 1 wt. % alkane; (b) contacting said first feedstock andsaid second feedstock with a first catalyst in said first reaction zoneto produce a first effluent, said first reaction zone being maintainedunder conditions such that said first reaction zone is predominatelyliquid phase, wherein at least 90 mole percent the alkene present insaid first feedstock is converted and said first effluent comprises analkylated aromatic compound and alkane; (c) cooling said first effluentwithout separation of said alkane from said first effluent; (d)supplying at least a portion of said cooled first effluent and a thirdfeedstock to said second reaction zone, wherein said third feedstock hasthe same composition as said second feedstock; and (e) contacting saidat least a portion of said cooled first effluent and said thirdfeedstock with a second catalyst in said second reaction zone to producea second effluent, said second reaction zone being maintained underconditions such that said second reaction zone is in a predominatelyliquid phase; wherein said the reactor is operated to achieveessentially complete conversion of the alkene.
 2. The process of claim1, wherein said first and second catalysts are a molecular sieveselected from the group consisting of MCM-22, MCM-36, MCM-49 and MCM-56,beta zeolite, faujasite, mordenite, PSH-3, SSZ-25, ERB-1, ITQ-1, ITQ-2,zeolite Y, Ultrastable Y (USY), Dealuminized Y, rare earth exchanged Y(REY), ZSM-3, ZSM-4, ZSM-18, ZSM-20, or any combination thereof.
 3. Theprocess of claim 1 wherein said conditions in steps (b) and (e) includea temperature of 120 to 285° C. and a pressure of 689 to 4601 kPa-a (100to 667 psia), a WHSV based on the weight of alkene of 0.1 to 10 h⁻¹. 4.The process of claim 1 wherein said second and third feedstocks comprisea first alkene component and a second alkene component.
 5. The processof claim 4 wherein said first alkene component comprises 99 mol. % to100 mol. % of said alkenes.
 6. The process of claim 4 wherein saidsecond alkene component comprises at least 20 mol. % alkene.
 7. Theprocess of claim 4 wherein said second alkene component comprises from20 to 80 mol. % alkene.
 8. (canceled)
 9. The process of claim 1, furthercomprising the step of: (f) separating said second effluent to recoversaid alkylated aromatic compound.
 10. The process of claim 1 whereinsaid alkylated aromatic compound comprises ethylbenzene, said firstfeedstock comprises benzene, and said second feedstock and said thirdfeedstock comprise a mixture of ethylene and ethane.
 11. The process ofclaim 1 wherein said alkylated aromatic compound comprises cumene, saidfirst feedstock comprises benzene, and said second feedstock and saidthird feedstock comprise a mixture of propylene and propane.
 12. Theprocess of claim 1 comprises the further step of contacting said firstfeedstock and a fourth feedstock with an alkylation catalyst in aby-passable pre-reactor upstream of said reactor, wherein said fourthfeedstock comprises an alkene.
 13. The process of claim 1 comprises thefurther step of contacting said second effluent under alkylationconditions with an alkylation catalyst in a finishing-reactor downstreamof said reactor.
 14. A process for producing an alkylated aromaticcompound as recited in claim 1, wherein said second effluent comprisessaid alkylated aromatic compound and polyalkylated aromatic compoundsand said process further comprises; (a) separating at least a portionsaid first and/or second effluents to recover said polyalkylatedaromatic compound(s) to form a transalkylation feed stream; and (b)contacting at least a portion of said transalkylation feed stream with afourth feedstock in the presence of a transalkylation catalyst toproduce a transalkylation effluent under transalkylation conditions,wherein said fourth feedstock comprises an alkylatable aromaticcompound(s), said transalkylation effluent which comprises saidalkylated aromatic compound.
 15. The process of claim 14, furthercomprising the steps of: (c) separating said transalkylation effluent torecover said alkylated aromatic compound.
 16. The process of claim 14,wherein said transalkylation catalyst is a molecular sieve selected fromthe group consisting of MCM-22, MCM-36, MCM-49 and MCM-56, beta zeolite,faujasite, mordenite, PSH-3, SSZ-25, ERB-1, ITQ-1, ITQ-2, zeolite Y,Ultrastable Y (USY), Dealuminized Y, rare earth exchanged Y (REY),ZSM-3, ZSM-4, ZSM-18, ZSM-20, or any combination thereof.
 17. Theprocess of claim 14, wherein said transalkylation conditions include atemperature of 150 to 260° C. and a pressure of 696 to 4137 kPa-a (101to 600 psia), a WHSV based on the weight of said polyalkylated aromaticcompounds of about 0.5 to 100 h⁻¹, a mole ratio of said alkylatablearomatic compound to said polyalkylated aromatic compounds of 1:1 to10:1.
 18. The process of claim 1, wherein said alkylated aromaticcompound is ethylbenzene.
 19. The process of claim 1, wherein saidalkylated aromatic compound is cumene.